Synergistic antioxidant composition of the acidic type



Patented Apr. 21, 1943 UNITED. .SIATES. PATENT OFFICE 7 Claims. (Cl. 280-898.5)

(Granted under the act of March 3, 1883, as amended April 30, 1928: 370 0. G. 757) This application is made under the act of March 3, 1883, as amended by the act of April 30, 1928, and the invention herein described, if patented, may be manufactured and usedby or for the Government of the United States of America for governmental purposes without the payment to us of any royalty thereon.

This invention relates to antioxidant composstions, and more particularly to rancidity inhibitors for fats and oils.

To inhibit oxidative rancidity, the objectionable odor and flavor imparted to fats and oils by the action of atmospheric oxygen, it is common practice to incorporate various antioxidants or rancidity-inhibiting agents with oleaginous materials.

Rancidity inhibitors may be classified into three groups:

1. Acidic inhibitors, such as phosphoric, oxalic, citric, tartaric, ascorbic and malic acids.

2. Inhibitols," natural compounds occurring in the unsaponiflable fraction of vegetable oils,

for example, alpha-tocopherol (vitamin E) and its isomers and analogues.

3. Phenolic inhibitors, for instance, pyrogallol, catechol, alphanaphthol' and hydroquinone.

A synergistic or enhancing antioxidant efiect has heretofore been observed for some rancidityv esters of fat acids are fat soluble substances 3 having excellent rancidity-inhibiting properties. We have found that synergistic antioxidant action results when acidic inhibitors are used in The term "ascorbyl monoesters of fat acids," as used herein, is defined as the monesters of saturated aliphatic monocarboxylic acids containing from 12 to 18 carbon atoms per molecule with compounds of the ascorbic acid series having the general formula:

where a: represents 0 or a whole number not exceeding 3. Thus, the term ascorbyl esters of fat acids" is meant to include such compounds as the palmityl, stearyl, myristyi, lauryl esters of dand l-ascorbic and isoascorbic acids, or 01' other compounds of the ascorbic acid series, used either singly or in combination.

Ascorbyl monoesters of fat acids are obtain,- able by the interaction of compounds of the ascorbic acid series with aliphatic monocarboxylic acids in the presence of'concentrated sulfuric acid, according to methods described -a length of time necessary to eflect esterification, which usually requires 16 to 20 hours. The

. -monoester is then isolated from the sulfuric acid conjunction with phospholipids, for example,

soybean phospholipids (commercial lecithin).

- The acidic component may be a compound con taining a hydroxyl roup or a carboxyl group, or both, or a compound containing an amino group and a carboxyl group. For example, a marked increase in stability results when small amounts of soybean phospholipids and ascorbyl monoesters of fat acids are added to fatty material. This increase in stability is much greater than the additive eflect of either substance used singly.

solution by any suitable procedure; for instance, by dilution with water followed by solvent extraction.

The method of preparing these monoesters is further illustrated by the following examples:'

Example I l-ascorbyl palmitate, the palmitic acid monoester of l-ascorbic acid, is prepared by dissolving 8.8- grams of l-ascorbic acid and 10.3 grams of palmitic acid in 100 cc. of percent sulfuric acid at essentially room temperature. The soluyield is good.

is good.

acid. The ether extract is then dried and ev apoi;

rated to dryness and the residue powdered and washed by decantation. with 200 to 300 cc. of petroleum ether (boiling range 35 to 60 0.), thereby removing unreacted palmitic- "acid from the reaction product.

The white solid residue is insoluble in petroleum ether and consists essentially of ascorbyi monopalmitate. The

Example II 8.8v grams of d-isoascorbic acid are esterifled with 10.8 grams of palmitic acid in 100 cc. of 95 percent sulfuric acid by the procedure described in Example I. The reaction product after removal oi unreacted palmitic acid consists essentially o! d-isoascorbyl monopalmitate. The yield Our invention is illustrated by the following tabulations 01 experimental data. In these tables the stability of the tested materials is indicated by the length or time required to attain a peroxide content equal to 20 mini-equivalents per kilogram of the fatty substrate. The stability was determined by the Swift stability test, also known as the "Active oxygen method," in which air is bubbled at a uniform and definite rate'through samples or the fatty material maintained at 100 C. At regular intervals the samples are tested for peroxide content by determining the amount of tree iodine liberated from potassium iodide by the peroxide-like oxidation products i'ormed in the fatty material.

Table I Rancidity-inhibiting agents added .Bubstrate w Aseorbyl Monoester pa eant I Mcnoestsr used gag? Table II Humidity-inhibiting scents added Sia- Subsiraio used Soybean mmbm' 7 hours lipid" Amount per cent Inhibitor used W cent 7 .10 0. 10 7 J do 0. 10 12 4 0. 10 8 4. Do ..do 0. 10 Do..... Tartsryl pslmitate.. 0. 29 ll Do..... 0.03 7 4n 0. 29 Do d-isoascorbic acid. 0. 10 90...... 0. 03 ..-..do 0.10 l-asoorbic acid 0.10 w 0.03 do 0. lo 47% Our invention is not limited to the specific ex- .ampleslisted in the above tables. It is applicable to any oleaginous material of the glyceride type or other esters or fat-acids.

. Having thus described our invention, we claim: 1. An antioxidant composition comprising phowholipids nd anascorbyl monoester of a saturated aliphatic monocarboxylic acid containing 12 to lacarbon atoms per molecule.

2. An antioxidant composition comprising soybean phospholipids and isoascorbyl monostearate.

3. The method of inhibiting oleaginous materials or the glyceride type and other esters ct fat acids against oxidative rancidity. which comprises incorporating therewith phospholipids and an ascorbyl monoester or fat acids.

4. The method of inhibiting oleaginous materials oi the glyceride type and other esters of fat acids against oxidative rancldity, which comprises incorporating therewith soybean phospholipids and an ascorbyl monoester of fat acids.

5. An oleaginous composition comprising esters of fat acids. having. incorporated therein in amounts suflicient to inhibit the development of oxidative rancidity. phospholipids, and an ascorbyl monoester oi. rat acids.

6. An oleaginous composition comprising esters of let acids. having incorporated therein in amounts suflicient to inhibit'the development of oxidative rancidity, soybean phospholipids, and an I ascorbyl monoester of fat acids.

7. An antioxidant composition consisting of phospholipids and an ascorbyl monoester of a saturated aliphatic monocarboxylic acid containing 12 to 18 carbon atoms per molecule.

ROY W, RIEMENSCHNEIDER. JACK TURER.

REFERENCES crr zn The following references are of record in the his of this-\patent:

UNITED s'ra'ms PATENTS OTHER REFERENCES Jr. Am. Chem. 800.. Nov. 1936, pp. 2204-8. Food Industries, Nov. 1942, pare '14. 

